Threading questions - using tap/die set

[Jason Hallowell]

So what's the difference between tap and dies for steel and tap and dies for wood?

All the ones I've seen looked more like a standard bolt and nut with handles, and don't have the flutes that create the cutting edges on the taps and dies for metal.

When I used them, they seemed to compress the wood fibers to the threaded shape rather than cut them. This seemed to make stronger threads than the taps and dies for metal that end up tearing the wood fibers, but still not as strong as actually cutting it into the threaded shape.

I would think taps and dies could be made like the ones for metal, but with the flutes ground at a different angle to cut wood better, but I've never seen anything like that. Maybe the more severe angle needed would dull to quickly to be practical.

[Bill Stevener]

But, I did want to experiment with the taps and dies to see what could be done. I'll post some pix today - I promise.

Well the day is not over, however it is about 10:00 pm. at my home.

What ever happened to the picture police on this Chanel???

[Jim Underwood]

As promised.... It's still today by my clock at 11:35. Sorry to make you wait. I was trying to fill an order for some small spindle work in the shop, and I just now got back in the house and got cleaned up...

The first picture is a shotgun shell sized box made of Osage Orange. It's open so you can see the threads. You can see they are pretty clean.

You can also see how I managed to use a steel cutting tap and die set on wood. The secret is I used a scrap piece turned cross grain for the threads. I first rough turned the box, parted off the lid, then drilled and tapped out the body. I used a little bigger drill than recommended as you want a little slop for wood threads. That goes pretty smoothly as you have plenty of support for the threads.

Then I chucked up the lid and estimated how thick I wanted the supporting "rod" for the cross grained piece I would use for threads. I think I used a 3/16 drill bit, so I sized the rod to that with dial calipers - within a couple thousandths of an inch so the glue joint would be strong. I then took a scrap piece of Osage Orange and drill it with the selected drill bit, and glued it in place. Then I turned it down to 1/2 inch or less (remember you want slop in the threads).

I was a little impatient so I used super glue, and didn't really wait long enough for it to dry, so the 1/2 x 13 die tended to twist the supporting rod a bit. If you look at the end grain of the lid, you'll see it stayed a little twisted. Once I got the threads cut, I cut a little relief at the shoulder, and cleaned up all the threads with a bit of sandpaper.

I then screwed the lid on, and finished up the top since the bottom was still in the chuck. Once that was done I chucked up the original drill I used on the body and stuck that in the head stock and reversed the body onto the drill, and brought up the tails stock to finish off the bottom of the box. Once you have a little nubbin left you move the tails stock and finesse that nubbin off, sand and finish.

Next time I'll chuck up the thread stock and turn it round, face it off, and then drill it while it's still in the chuck. That way I can get it to fit a bit better. I'll also glue it on the rod, and let it dry before trying to thread it.

The second picture is of the box with lid on.
The third picture is the first box I tried threading. The threads are 5/16 x 20. The inside threads were great, but the outside threads were a little sad. Even though the outside threads are rough, the action is pretty smooth.

You can see why I made a box... And that's a bit of a gloat. The smallest goblet (errr... Martini glass) is 3/16 high...

If I were a drinkin' man, it'd be time for a drink, but I think I'll go to bed instead.

[Bill Stevener]

You did make the day Jim.

If you wish to make items of wood with threads, like I said, invest in the tools for the job.
I use the Beall tool threading system, a little costly, however well worth it.
Notice the difference in the threads exhibited in the photos below, 1/2" threads. Entirely different shape.



Bill.>>>>>>>>>>>>>>>

[Jim Underwood]

Thanks for the advice Bill. One of these days I'll get some threading tools if I want to do some serious threading. I just wanted to explore possibilities. Sometimes they don't make the tooling in the sizes you want...

I should add that I used CA glue on the threads to harden the wood a bit. I also used a bit of paste wax to lubricate them. Seems to work pretty well.

I'm going to be putting together a threading jig for my boxes eventually. I haven't decided whether to use a router or my lathe to drive the live tooling. Either way it should be fun.

I'm also going to make or buy some thread chasers and see if I can learn to use them (even though my lathe will only slow down to 500 RPM). I may have to borrow a lathe in order to learn...

Like I said... I'm exploring the possibilities.

By the way, I've taken a look at your homemade lathe, (I can't seem to find the photos now), and I'm very impressed. Very cool stuff! I would love to come by and take a look if you weren't so far away... I've made the flywheel for a treadle lathe (and gotten no farther) but intend to finish it one day...